Pulmonary function tests (PFTs) are essential assessments of lung function, measuring various respiratory mechanics and gas exchange capabilities. They are indicated for diagnostics, prognostics, and preoperative evaluations, particularly in patients with risk factors such as age, obesity, or respiratory issues. Different testing methodologies include bedside assessments, static and dynamic lung volumes, and flow volume loops to detect airway obstructions and evaluate lung health.

1. PULMONARY FUNCTION TESTS

2. INTRODUCTION
• Pulmonary function tests is a generic term used to
indicate a battery of studies or maneuvers that may
be performed using standardized equipment to
measure lung function.
Evaluates one or more aspects of the respiratory
system
– Respiratory mechanics
– Lung parenchymal function/ Gas exchange
– Cardiopulmonary interaction

3. INDICATIONS
DIAGNOSTIC PROGNOSTIC
Evaluation of signs & symptoms‐
BLN, chronic cough, exertional
dyspnea
Assess severity
Screening at risk pts Follow response to therapy
Measure the effect of Ds on Determine further treatment goals
pulmonary function
To assess preoperative risk Evaluating degree of disability
Monitor pulmonary drug toxicity

4. TISI GUIDELINES
• Age > 70
• Obese patients
• Thoracic surgery
• Upper abdominal surgery
• History of cough/ smoking
• Any pulmonary disease

5. American College of Physicians
Guidelines
 Lung resection
 H/o smoking, dyspnoea
 Cardiac surgery
 Upper abdominal surgery
 Lower abdominal surgery
 Uncharacterized pulmonary disease(defined as history of
pulmonary Disease or symptoms and no PFT in last 60 days)

6. Contraindications
• Recent eye surgery
• Thoracic , abdominal and cerebral aneurysms
• Active hemoptysis
• Pneumothorax
• Unstable angina/ recent MI within 1 month

7. INDEX
1. Categorization of PFT’s
2. Bedside pulmonary function tests
3. Static lung volumes and capacities
4. Measurement of FRC, RV
5. Dynamic lung volumes/forced spirometry
6. Physiological determinant of spirometry
7. Flow volume loops and detection of airway obstruction
8. Flow volume loop and lung diseases
9. Tests of gas exchange function
10. Tests for cardiopulmonary reserve
11. Preoperative assessment of thoracotomy patients

8. CATEGORIZATION OF PFT
• BED SIDE PULMONARY FUNCTION TESTS
• STATIC LUNG VOLUMES & CAPACITIES – VC, IC, IRV,
ERV, RV, FRC.
• DYNAMIC LUNG VOLUMES –FVC, FEV1, FEF 25‐75%,
PEFR, MVV, RESP. MUSCLE STRENGTH
MECHANICAL VENTILATORY
FUNCTIONS OF LUNG / CHEST WALL:

9. • A)Alveolar‐arterial po2 gradient
• B) Diffusion capacity
• C) Gas distribution tests‐ 1)single breath N2
test.2)Multiple Breath N2 test 3) Helium dilution
method 4) Radio Xe scinitigram.
GAS‐ EXCHANGE TESTS :

10. • Qualitative tests:
1) History , examination
2) ABG
• Quantitative tests
1) 6 min walk test
2) Stair climbing test
3)Shuttle walk
4) CPET(cardiopulmonary exercise testing)
CARDIOPULMONARY INTERACTION:

11. INDEX
1. Bedside pulmonary function tests
2. Static lung volumes and capacities
3. Measurement of FRC, RV
4. Dynamic lung volumes/forced spirometry
5. Flow volume loops and detection of airway obstruction
6. Flow volume loop and lung diseases
7. Tests of gas function
8. Tests for cardiopulmonary reserve
9. Preoperative assessment of thoracotomy patients

12. Bed side pulmonary function tests
RESPIRATORY RATE
‐ Essential yet frequently undervalued
component of PFT
‐ Imp evaluator in weaning & extubation
protocols
Increase RR ‐ muscle fatigue ‐ work load ‐ weaning fails

13. Bed side pulmonary function tests
1) Sabrasez breath holding test:
Ask the patient to take a full but not too deep breath & hold
it as long as possible.
• >25 SEC.‐NORMAL Cardiopulmonary Reserve (CPR)
• 15‐25 SEC‐ LIMITED CPR
• <15 SEC‐ VERY POOR CPR (Contraindication for
elective surgery)
25‐ 30 SEC ‐ 3500 ml VC
20 – 25 SEC ‐ 3000 ml VC
15 ‐ 20 SEC ‐ 2500 ml VC
10 ‐ 15 SEC ‐ 2000 ml VC
10 SEC ‐ 1500 ml VC
‐
5

14. Bed side pulmonary function tests
2) SCHNEIDER’S MATCH BLOWING TEST: MEASURES Maximum
Breathing Capacity.
Ask to blow a match stick from a distance of 6” (15 cms)
with‐
 Mouth wide open
 Chin rested/supported
 No purse lipping
 No head movement
 No air movement in the room
 Mouth and match at the same level

15. Bed side pulmonary function tests
• Can not blow out a match
– MBC < 60 L/min
– FEV1 < 1.6L
• Able to blow out a match
– MBC > 60 L/min
– FEV1 > 1.6L
• MODIFIED MATCH TEST:
DISTANCE MBC
9” >150 L/MIN.
6” >60 L/MIN.
3” > 40 L/MIN

16. Bed side pulmonary function tests
3)COUGH TEST: DEEP BREATH F/BY COUGH
 ABILITY TO COUGH
 STRENGTH
 EFFECTIVENESS
INADEQUATE COUGH IF: FVC<20 ML/KG
FEV1 < 15 ML/KG
PEFR < 200 L/MIN.
*A wet productive cough / self propagated paraoxysms of
coughing – patient susceptible for pulmonary Complication.

17. Bed side pulmonary function tests
4)FORCED EXPIRATORY TIME:
After deep breath, exhale maximally and forcefully & keep
stethoscope over trachea & listen.
N FET – 3‐5 SECS.
OBS.LUNG DIS. ‐ > 6 SEC
RES. LUNG DIS.‐ < 3 SEC

18. Bed side pulmonary function tests
5)WRIGHT PEAK FLOW METER: Measures PEFR (Peak Expiratory
Flow Rate)
N – MALES‐ 450‐700 L/MIN.
FEMALES‐ 350‐500 L/MIN.
<200 L/ MIN. – INADEQUATE COUGH EFFICIENCY.
6)DE‐BONO WHISTLE BLOWING TEST: MEASURES PEFR.
Patient blows down a wide bore tube at the end of which is a
whistle, on the side is a hole with adjustable knob.
As subject blows → whistle blows, leak hole is gradually
increased till the intensity of whistle disappears.
At the last position at which the whistle can be blown , the
PEFR can be read off the scale.

19. DEBONO’S WHISTLE

20. Bed side pulmonary function tests
• MICROSPIROMETERS – MEASURE VC.
• BED SIDE PULSE OXIMETRY
• ABG.

21. INDEX
1. Bedside pulmonary function tests
2. Static lung volumes and capacities
3. Measurement of FRC, RV
4. Dynamic lung volumes/forced spirometry
5. Flow volume loops and detection of airway obstruction
6. Flow volume loop and lung diseases
7. Tests of gas function
8. Tests for cardiopulmonary reserve
9. Preoperative assessment of thoracotomy patients

22. STATIC LUNG VOLUMES AND
CAPACITIES
• SPIROMETRY : CORNERSTONE OF ALL PFTs.
• John hutchinson – invented spirometer.
• “Spirometry is a medical test that measures the
volume of air an individual inhales or exhales as a
function of time.”
• CAN’T MEASURE – FRC, RV, TLC

23. SPIROMETRY‐Acceptability Criteria
• Good start of test‐ without any hesitation
• No coughing / glottic closure
• No variable flow
• No early termination(> 6 sec)
• No air leak
• Reproducibility‐ The test is without excessive variability
The two largest values for FVC and the two largest values for
FEV1 should vary by no more than 0.2L.

24. SPIROMETRY‐Acceptability Criteria

25. Spirometry Interpretation: So what
constitutes normal?
• Normal values vary and depend on:
I. Height – Directly proportional
II. Age – Inversely proportional
III. Gender
IV. Ethnicity

26. LUNG VOLUMES AND CAPACITIES
PFT tracings have:
Four Lung volumes: tidal
volume, inspiratory reserve
volume, expiratory reserve
volume, and residual volume
Five capacities: inspiratory
capacity, expiratory capacity,
vital capacity, functional residual
capacity, and total lung capacity
Addition of 2 or more volumes comprise a capacity.

27. LUNG VOLUMES
• Tidal Volume (TV): volume of
air inhaled or exhaled with
each breath during quiet
breathing (6‐8 ml/kg) 500 ml
• Inspiratory Reserve Volume
(IRV): maximum volume of air
inhaled from the end‐
inspiratory tidal position.3000
ml
• Expiratory Reserve Volume
(ERV): maximum volume of
air that can be exhaled from
resting end‐expiratory tidal
position.1500 ml

28. LUNG VOLUMES
• Residual Volume (RV):
– Volume of air remaining in
lungs after maximium
exhalation (20‐25 ml/kg)
1200 ml
– Indirectly measured (FRC‐
ERV)
– It can not be measured by
spirometry .

29. LUNG CAPACITIES
• Total Lung Capacity (TLC): Sum of
all volume compartments or
volume of air in lungs after
maximum inspiration (4‐6 L)
• Vital Capacity (VC): TLC minus RV
or maximum volume of air
exhaled from maximal inspiratory
level. (60‐70 ml/kg) 5000ml. VC ~
3 TIMES TV FOR EFFECTIVE
COUGH
• Inspiratory Capacity (IC): Sum of
IRV and TV or the maximum
volume of air that can be inhaled
from the end‐expiratory tidal
position. (2400‐3800ml).
• Expiratory Capacity (EC): TV+ ERV

30. LUNG CAPACITIES
• Functional Residual Capacity
(FRC):
– Sum of RV and ERV or the
volume of air in the lungs at
end‐expiratory tidal
position.(30‐35 ml/kg) 2500 ml
– Decreases
1.in supine position(0.5‐1L)
2.Obese pts
3.Induction of anesthesia: by 16‐
20%

31. FUNCTION OF FRC
• Oxygen store
• Buffer for maintaining a steady arterial po2
• Partial inflation helps prevent atelectasis
• Minimizes the work of breathing

32. INDEX
1. Bedside pulmonary function tests
2. Static lung volumes and capacities
3. Measurement of FRC, RV
4. Dynamic lung volumes/forced spirometry
5. Flow volume loops and detection of airway obstruction
6. Flow volume loop and lung diseases
7. Tests of gas function
8. Tests for cardiopulmonary reserve
9. Preoperative assessment of thoracotomy patients

33. Measuring RV, FRC
It can be measured by
– nitrogen washout technique
– Helium dilution method
– Body plethysmography

34. N2 Washout Technique
• The patient breathes 100% oxygen, and all the
nitrogen in the lungs is washed out.
• The exhaled volume and the nitrogen
concentration in that volume are measured.
• The difference in nitrogen volume at the initial
concentration and at the final exhaled
concentration allows a calculation of
intrathoracic volume, usually FRC.

35. Helium Dilution technique
• Pt breathes in and out from a reservoir with known
volume of gas containing trace of helium.
• Helium gets diluted by gas previously present in lungs.
• eg: if 50 ml Helium introduced and the helium
concentration is 1% , then volume of the lung is 5L.

36. Body Plethysmography
• Plethysmography (derived from greek word meaning
enlargement).
• Based on principle of BOYLE’S LAW(P*V=k)
• Priniciple advantage over other two method is it
quantifies non‐ communicating gas volumes.

37. • A patient is placed in a sitting
position in a closed body box
with a known volume
• The patient pants with an
open glottis against a closed
shutter to produce changes
in the box pressure
proportionate to the volume
of air in the chest.
• As measurements done at
end of expiration, it yields
FRC

38. INDEX
1. Bedside pulmonary function tests
2. Static lung volumes and capacities
3. Measurement of FRC, RV
4. Dynamic lung volumes/forced spirometry
5. Flow volume loops and detection of airway obstruction
6. Flow volume loop and lung diseases
7. Tests of gas function
8. Tests for cardiopulmonary reserve
9. Preoperative assessment of thoracotomy patients

39. FORCED SPIROMETRY/TIMED EXPIRATORY
SPIROGRAM
Includes measuring:
• pulmonary mechanics – to
assess the ability of the lung to
move large vol of air quickly
through the airways to identify
airway obstruction
• FVC
•FEV1
•Several FEF values
•Forced inspiratory rates(FIF’s)
•MVV

40. FORCED VITAL CAPACITY
• The FVC is the maximum volume of air that can be
breathed out as forcefully and rapidly as possible
following a maximum inspiration.
• Characterized by full inspiration to TLC followed by
abrupt onset of expiration to RV
• Indirectly reflects flow resistance property of
airways.

41. FORCED VITAL CAPACITY

42. FVC
 Interpretation of % predicted:
 80-120% Normal
 70-79%
Mild reduction
 50%-69% Moderate reduction
 <50% Severe reduction
FVC

43. Measurements Obtained from the FVC
Curve and their significance
• Forced expiratory volume
in 1 sec(FEV1 )‐‐‐the
volume exhaled during
the first second of the
FVC maneuver.
• Measures the general
severity of the airway
obstruction
• Normal is 3‐4.5 L

44. Measurements Obtained from the FVC
Curve and their significance
FEV1 – Decreased in both obstructive & restrictive lung
disorders(if patient’s vital capacity is smaller than predicted
FEV1).
FEV1/FVC – Reduced in obstructive disorders.
Interpretation of % predicted:
 >75% Normal
 60%‐75% Mild obstruction
 50‐59% Moderate obstruction
 <49% Severe obstruction

45. Measurements Obtained from the FVC
Curve and their significance

46. Forced midexpiratory flow 25‐75% (FEF25‐
75)
• Max. Flow rate during the
mid‐expiratory part of FVC
maneuver.
 Measured in L/sec
 May reflect effort
independent expiration
and the status of the small
airways
 Highly variable
 Depends heavily on FVC
• N value – 4.5‐5 l/sec. Or 300
l/min.

47. Forced midexpiratory flow 25‐75% (FEF25‐
75)
Interpretation of % predicted:
 >60% Normal
 40‐60% Mild obstruction
 20‐40% Moderate obstruction
 <10% Severe obstruction

48. Peak expiratory flow rates
• Maximum flow rate during an FVC maneuver occurs in initial
0.1 sec
• After a maximal inspiration, the patient expires as forcefully
and quickly as he can and the maximum flow rate of air is
measured.
• Forced expiratory flow between 200‐1200ml of FVC
• It gives a crude estimate of lung function, reflecting larger
airway function.
• Effort dependant but is highly reproductive

49. Peak expiratory flow rates
• It is measured by a peak flow meter,
which measures how much air (litres
per minute)is being blown out or by
spirometry
• The peak flow rate in normal adults
varies depending on age and height.
• Normal : 450 ‐ 700 l/min in males
300 ‐ 500 l/min in females
• Clinical significance ‐ values of <200/l‐
impaired coughing & hence likelihood
of post‐op complication

50. Maximum Voluntary Ventilation (MVV) or
maximum breathing capacity (MBC)
• Measures ‐ speed and efficiency of filling &
emptying of the lungs during increased respiratory
effort
• Maximum volume of air that can be breathed in and
out of the lungs in 1 minute by maximum voluntary
effort
• It reflects peak ventilation in physiological demands
• Normal : 150 ‐175 l/min. It is FEV1 * 35
• <80% ‐ gross impairment

51. Maximum Voluntary Ventilation (MVV) or
maximum breathing capacity (MBC)
• The subject is asked to breathe as
quickly and as deeply as possible
for 12 secs and the measured
volume is extrapolated to 1min.
• Periods longer than 15 seconds
should not be allowed because
prolonged hyperventilation leads
to fainting due to excessive
lowering of arterial pCO2 and H+.
• MVV is markedly decreased in
patients with
A. Emphysema
B. Airway obstruction
C. Poor respiratory muscle strength

52. TO SUMMARISE

53. PHYSIOLOGICAL DETERMINANTS OF MAX.
FLOW RATES
1)DEGREE OF EFFORT‐ driving pressure generated by muscle
contraction (PEmax & PI max)
2) ELASTIC RECOIL PRESSURE OF LUNG: (PL)
 Tendency to recoil or collapse d/t PL
 PL increases from RV (2‐3) to TLC (20‐30)
 Opposed by Pcw (recoil pr. Of chest wall)
 Prs=Pl + Pcw = 0 at FRC‐resting state
(Prs‐recoil pr.of resp.system)
3) AIRWAY RESISTANCE (Raw):
 Determined by the calibre of airways
 Decreases as lung vol increases (hyperbolic curve)
 Raw high at RV & low at TLC

54. INDEX
1. Bedside pulmonary function tests
2. Static lung volumes and capacities
3. Measurement of FRC, RV
4. Dynamic lung volumes/forced spirometry
5. Flow volume loops and detection of airway obstruction
6. Flow volume loop and lung diseases
7. Tests of gas function
8. Tests for cardiopulmonary reserve
9. Preoperative assessment of thoracotomy patients

55. FLOW VOLUME LOOPS
 “Spirogram” Graphic analysis of flow at various lung volumes
 Tracing obtained when a maximal forced expiration from TLC
to RV is followed by maximal forced inspiration back to TLC
 Measures forced inspiratory and expiratory flow rate
 Augments spirometry results
 Principal advantage of flow volume loops vs. typical standard
spirometric descriptions ‐ identifies the probable obstructive
flow anatomical location.

56. FLOW VOLUME LOOPS
• First 1/3rd of expiratory flow is effort
dependent and the final 2/3rd near
the RV is effort independent
• Inspiratory curve is entirely effort
dependent
• Ratio of
– maximal expiratory flow(MEF)
/maximal inspiratory flow(MIF)
– mid VC ratio and is normally 1

57. FLOW VOLUME LOOPS and DETECTION OF
UPPER AIRWAY OBSTRUCTION
• flow‐volume loops provide
information on upper airway
obstruction:
Fixed obstruction: constant
airflow limitation on
inspiration and expiration—
such as
1. Benign stricture
2. Goiter
3. Endotracheal neoplasms
4. Bronchial stenosis

58. FLOW VOLUME LOOPS and DETECTION OF
UPPER AIRWAY OBSTRUCTION
Variable intrathoracic obstruction:
flattening of expiratory limb.
1.Tracheomalacia
2. Polychondritis
3. Tumors of trachea or main
bronchus
• During forced expiration – high pleural
pressure – increased intrathoracic pressure ‐
decreases airway diameter. The flow volume
loop shows a greater reduction in the
expiratory phase
• During inspiration – lower pleural pressure
around airway tends to decrease obstruction

59. FLOW VOLUME LOOPS and DETECTION OF
UPPER AIRWAY OBSTRUCTION
Variable extrathoracic obstruction:
1.Bilateral and unilateral vocal cord
paralysis
2. Vocal cord constriction
3. Chronic neuromuscular disorders
4. Airway burns
5. OSA
• Forced inspiration‐ negative transmural
pressure inside airway tends to collapse it
• Expiration – positive pressure in airway
decreases obstruction
• inspiratory flow is reduced to a greater extent
than expiratory flow

60. INDEX
1. Bedside pulmonary function tests
2. Static lung volumes and capacities
3. Measurement of FRC, RV
4. Dynamic lung volumes/forced spirometry
5. Flow volume loops and detection of airway obstruction
6. Flow volume loop and lung diseases
7. Tests of gas function
8. Tests for cardiopulmonary reserve
9. Preoperative assessment of thoracotomy patients

61. Obstructive Pattern — Evaluation
Common obstructive lung diseases
• Asthma
• COPD (chronic bronchitis, emphysema)
• Cystic fibrosis.

62. ASTHMA
 Peak expiratory flow reduced so
maximum height of the loop is
reduced
 Airflow reduces rapidly with the
reduction in the lung volumes
because the airways narrow and
the loop become concave
 Concavity may be the indicator of
airflow obstruction and may
present before the change in FEV1
or FEV1/FVC

63. EMPHYSEMA
Airways may collapse during
forced expiration because of
destruction of the supporting lung
tissue causing very reduced flow at
low lung volume and a
characteristic (dog‐leg) appearance
to the flow volume curve

64. REVERSIBILITY
• Improvement in FEV1 by 12‐15% or
200 ml in repeating spirometry after
treatment with Sulbutamol 2.5mg or
ipratropium bromide by nebuliser
after 15‐30 minutes
• Reversibility is a characterestic
feature of B.Asthma
• In chronic asthma there may be only
partial reversibility of the airflow
obstruction
• While in COPD the airflow is
irreversible although some cases
showed significant improvement

65. RESTRICTIVE PATTERN
Characterized by reduced lung
volumes/decreased lung
compliance
Examples:
•Interstitial Fibrosis
•Scoliosis
•Obesity
•Lung Resection
•Neuromuscular diseases
•Cystic Fibrosis

66. RESTRICTIVE PATTERN‐flow volume loop
• low total lung capacity
• low functional residual capacity
• low residual volume.
• Forced vital capacity (FVC) may be
low; however, FEV1/FVC is often
normal or greater than normal due
to the increased elastic recoil
pressure of the lung.
• Peak expiratory flow may be
preserved or even higher than
predicted leads to tall,narrow and
steep flow volume loop in
expiratory phase.

67. INDEX
1. Bedside pulmonary function tests
2. Static lung volumes and capacities
3. Measurement of FRC, RV
4. Dynamic lung volumes/forced spirometry
5. Flow volume loops and detection of airway obstruction
6. Flow volume loop and lung diseases
7. Tests for gas exchange function
8. Tests for cardiopulmonary reserve
9. Preoperative assessment of thoracotomy patients

68. TESTS FOR GAS EXCHANGE FUNCTION
ALVEOLAR‐ARTERIAL O2 TENSION GRADIENT:
 Sensitive indicator of detecting regional V/Q inequality
 N value in young adult at room air = 8 mmHg to up to 25
mmHg in 8th decade (d/t decrease in PaO2)
 AbN high values at room air is seen in asymptomatic smokers
& chr. Bronchitis (min. symptoms)
A‐a gradient = PAO2 ‐ PaO2
* PAO2 = alveolar PO2 (calculated from the alveolar gas
equation)
* PaO2 = arterial PO2 (measured in arterial gas)
PAO2:
(PB ‐ PH2O)*FiO2 ‐ (PaCO2/RQ)

69. TESTS FOR GAS EXCHANGE FUNCTION
DIFFUSING CAPACITY
• Rate at which gas enters the blood divided by its driving pressure
( gradient – alveolar and end capillary tensions)
• Measures ability of lungs to transport inhaled gas from alveoli to
pulmonary capillaries
• Normal‐ 20‐30 ml/min/mm Hg
• Depends on:
‐ thickeness of alveolar—capillary membrane
‐ hemoglobin concentration
‐ cardiac output

70. TESTS FOR GAS EXCHANGE FUNCTION
SINGLE BREATH TEST USING CO
• Pt inspires a dilute mixture of CO and hold the breath for 10 secs.
• CO taken up is determined by infrared analysis:
• DlCO = CO ml/min/mmhg
PACO – PcCO
• DLO2 = DLCO x 1.23
• Why CO?
A) High affinity for Hb which is approx. 200 times that of O2 , so
does not rapidly build up in plasma
B) Under N condition it has low bld conc ≈ 0
C) Therefore, pulm conc.≈0

71. FACTORS EFFECTING DLCO
DECREASE(< 80% predicted) INCREASE(> 120‐140%
predicted)
Anemia Polycythemia
Carboxyhemoglobin Exercise
Pulmonary embolism Congestive heart failure
Diffuse pulmonary fibrosis
Pulmonary emphysema
Predicted DLCO for Hb= Predicted DLCO * (1.7 Hb/10.22 + Hb)

72. INDEX
1. Bedside pulmonary function tests
2. Static lung volumes and capacities
3. Measurement of FRC, RV
4. Dynamic lung volumes/forced spirometry
5. Flow volume loops and detection of airway obstruction
6. Flow volume loop and lung diseases
7. Tests of gas function
8. Tests for cardiopulmonary reserve
9. Preoperative assessment of thoracotomy patients

73. CARDIOPULMONARY INTERACTION
• Stair climbing and 6‐minute walk test
• This is a simple test that is easy to perform with minimal
equipment. Interpretated as in the following table:
Performance VO2 Interpretation
max(ml/kg/min)
>5 flight of stairs > 20 Low mortality after
pneumonectomy, FEV1>2l
>3 flight of stairs Low mortality after lobectomy,
FEV1>1.7l
<2 flight of stairs Correlates with high mortality
<1 flight of stairs <10
6 min walk test <600 m <15

74. CARDIOPULMONARY INTERACTION
• Shuttle walk
• The patient walks between cones 10 meters apart with
increasing pace.
• The subject walks until they cannot make it from cone to
cone between the beeps.
• Less than 250m or decrease SaO2 > 4% signifies high risk.
• A shuttle walk of 350m correlates with a VO2 max of 11ml.kg‐
1.min‐1

75. Cardiopulmonary Exercise Testing
Non invasive technique
Effort independent
To test ability of subjects physiological response to
cope with metabolic demands

76. Basic Physiological Principles
• Exercising muscle gets energy from 3 sources‐ stored energy
(creatine phosphate), aerobic metabolism of glucose,
anaerobic metabolism of glucose
• In exercising muscle when oxygen demand exceeds supply‐
lactate starts accumulating‐ lactate anaerobic threshold (
LAT)
• With incremental increase in exercise – expired minute
volume, oxygen consumption per minute, CO2 production
per minute increases

77. What To Measure
◦ Anaerobic threshold (> 11 ml/kg/min)
◦ Maximum oxygen utilization VO2 (>20ml/kg/min)
◦ Ventilatory equivalent of O2 (< 35L)
◦ Ventilatory equivalent of CO2 (<42L)
◦ Oxygen pulse (4‐6ml/heart beat)

78. INDEX
1. Bedside pulmonary function tests
2. Static lung volumes and capacities
3. Measurement of FRC, RV
4. Dynamic lung volumes/forced spirometry
5. Flow volume loops and detection of airway obstruction
6. Flow volume loop and lung diseases
7. Tests of gas function
8. Tests for cardiopulmonary reserve
9. Preoperative assessment of thoracotomy patients

79. Assessment of lung function in
thoracotomy pts
• As an anesthesiologist our goal is to :
1) to identify pts at risk of increased post‐op morbidity &
mortality
2) to identify pts who need short‐term or long term post‐op
ventilatory support.
Lung resection may be f/by – inadequate gas exchange, pulm
HTN & incapacitating dyspnoea.

80. Assessment of lung function in
thoracotomy pts
Calculating the predicted postoperative
FEV1 (ppoFEV1) and TLCO (ppoTLCO):
There are 5 lung lobes containing
19 segments in total with the division of each
lobe.
Ppo FEV1=preoperative FEV1 * no. of segments
left after resection
19
• Can be assessed by ventilation perfusion scan. For eg:
A 57-year-old man is booked for lung
resection. His CT chest show a large RUL
mass confirmed as carcinoma:
ppoFEV1= 50*16/19=42%

81. Assessment of lung function in
thoracotomy pts
ppoFEV1(% predicted) Interpretation
> 40 No or minor respiratory complications
anticipated
< 40 Likely to require postoperative
ventilation/increased risk of
death/complication
< 30 Non surgery management should be
considered
ppoDLCO(% predicted) Interpretation
> 40,ppoFEV1> 40%,SaO2>90% on air Intermediate risk , no further investigation
needed
< 40 Increased respiratory and cardiac morbidity
< 40 and ppoFEV1<40% High risk‐ require cardiopulmonary exercise
test

82. In addition to history , examination , chest X‐ ray, PFT’s pre‐ op
evaluation includes:
• ventilation perfusion scintigraphy/ CT scan
• split‐lung function tests
 methods have been described to try and simulate the
postoperative respiratory situation by unilateral exclusion of a
lung or lobe with an endobronchial tube/blocker or by
pulmonary artery balloon occlusion of a lung or lobe artery

83. Combination tests
• There is no single measure that is a ‘Gold standard ‘
in predicting post‐op complications
Three legged stool
Respiratory
mechanics
FEV1(ppo>40%)
MVV,RV/TLC,FVC
Cardiopulmonary
reserve
Vo2max (>15ml/kg/min)
Stair climb > 2 flights, 6
min walk,
Exercise Spo2 <4%
Lung parenchymal
function
DL co (ppo>80%)
PaO2>60
Paco2<45

84. Pulmonary function criteria suggesting increased risk of post‐
operative pulmonary complications for various surgeries
Parameters Abdominal Thoracic
FVC < 70 % predicted < 2 lit. or < 70% predicted
FEV1 < 70 % predicted < 2 lit. – pneumonectomy
< 1 lit. – lobectomy
< 0.6 lit. – wedge or segmentectomy
FEV1/FVC < 65 % predicted < 50 % predicted
FEF 25‐75 % < 50 % predicted < 1.6 lit. – pneumonectomy
< 0.6 lit.‐ lobectomy/segmentectomy
MVV/MBC < 50 % predicted < 50 % predicted
PaCO2 > 45 mm Hg > 45 mm Hg

85. VC >LLN VC >LLN
TLC >LLN
Neuromuscular
diseases &chest
wall ds
TLC >LLN
Look at flow-vol loop and any
airway obstruction pattern
FEV1 /VC >LLN
Normal Restriction Obstruction mixed defects
DLCO>LLN DLCO>LLN
DLCO>LLN
Normal
ILD & pneumonitis
Asthma , bronchitis Emphysema
Pulmonary
Vascular Ds
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
Yes
No
No

86. Yes, PFTs are really wonderful but… They do not
act alone.
• They act only to support or exclude a
diagnosis.
• A combination of a thorough history and
physical exam, as well as supporting
laboratory data and imaging is helpful in
developing a anaesthetic plan for pt with
pulmonary dysfunction.